LAUSR

To overcome possible drawbacks of bone fracture reduction such as risks of malrotation, radiation exposure, as well as laborious traction, image-guided robotic surgery systems have been proposed. However, the use of optical tracking systems (OTS) creates inherent line-of-sight problems that cause frequent interruptions during surgery. We propose an OTS-free image-guided bone fracture reduction system utilizing a Stewart robot platform to solve the problem of conventional OTS-based robotic systems. The system applies inverse kinematics to compute the relative positions between the broken bone fragments. Each fragment is pre-operatively registered in the robotic system with a semi-automatic image-based registration method using an attachable jig designed for the proposed platform. This approach is particularly effective when the image features are not clearly detected in the fluoroscopic images. The accuracy of the proposed system was evaluated via pre- and post-operative computed tomography (CT) scans of femoral phantoms. Ex-vivo experiments were also performed on caprine legs to assess the clinical feasibility. In the phantom and ex-vivo experiments, the mean rotational errors of the reduction were 1.79° and 1.76°, respectively. The mean time for the reduction was approximately 3 min. This letter proposes a new method to compute the relative positions between the bone fragments using inverse kinematics and semi-automatic robot-patient registration without requiring a C-arm and an OTS. The OTS-free robotic surgery system has the potential advantages to enhance the accuracy of fracture reduction and reduce the surgery time and radiation exposure.